Crabgrass, Johnson grass, dandelions—such weeds can overcrowd lawns and pilfer air, water and nutrients that desirable plants need to survive and maintain a healthy appearance. Unchecked, weeds can completely dominate these plants, turning what could be a beautiful and verdant lawn into a wasteland of unsightly weeds. Keeping this in mind, it’s no wonder why so many clients are eager to pay qualified experts to swoop in and save their lawns from utter weed-spangled catastrophes.

And what better way to curtail weed growth than by stopping them before they’ve had a chance to break through the turf’s surface? Such is the philosophy behind pre-emergent controls. “By eliminating the weeds, we’re limiting the competition between them and the plants,” says Bryan Thompson, vice president for Pest Option, Anaheim, California. “The best way to get rid of weeds is to eliminate them when they’re still seeds.”

Pre-emergent control takes a very simple approach to reducing weeds with the use of chemical or biological herbicides (though they’re typically chemical). You create a barrier—or a weed prevention zone—in the top one to two inches of soil that prevents weeds from breaking the surface. This process falls under the umbrella of integrated pest management (IPM), a multiplestep program that promotes the judicious use of fertilizers and weed and insect control as it pertains to the health and appearance of turf.

“With IPM, you’re looking at the overall needs of the property from the get-go and then applying herbicides on an as-needed basis,” says Mike Sisti, marketing manager for Lebanon Seaboard Corporation, Lebanon, Pennsylvania. “You’re also integrating cultural practices to promote the turf. Herbicides play a big part in IPM, but you’re also going over the property and spottreating exactly where the weed problems are.”

Integrating weed control into your company’s services can be a great way to bring in extra revenue, as well as build new relationships with customers who want to clean up their lawn. Preemergence is most likely your safest bet in making a good impression. “The most effective control for weeds is pre-emergent, dollar for dollar,” says Thompson.

There’s a wide range of herbicides and IPM practices out there. Chemical herbicides seem to be the standard for today’s industry, but biological herbicides such as corn gluten meal can be used as well. It’s all a matter of knowing what your client expects. What kind of lawn do they want? What are their opinions so far as chemical herbicides go? And how do you continue to ensure a vibrant and healthy lawn after the pre-emergent controls have been applied? This article should help put things into perspective.

Chemical herbicides

Many factors need to be considered before choosing which chemical to apply. There’s a vast array of herbicides on the market, all of which are made to treat different kinds of plants in different kinds of weather. “There are a substantial number of herbicides coming into the market, and they’re constantly changing,” says Thompson. “The principle thing people need to do is research the material and know what they’re doing with it.”

Once you’ve pinned down the type of herbicide you’ll be using, you’ll want to know how to apply it. Again, depending on the type of herbicide you’ll be using, application procedures can vary. Always read the label on the side of the product to learn how it’s to be applied. By rule of thumb, herbicides should be bonded to the soil twice a year: once in the winter and once in the spring. Determining exactly when it’s time to cover the turf with herbicide is dependent on the region you’re in and how warm it is, but try to shoot for about two to four weeks before the weeds begin to germinate.

For Mark Urbanowski, senior marketing specialist for Dow Agro-Sciences, Indianapolis, Indiana, weeds will begin to sprout at about 50 to 55 degrees. “That’s the temperature where crabgrass and many other weeds start to germinate,” says Urbanowski. “So we’ll spread the herbicides before the soil gets to that temperature.” Once the temperatures warm up enough, the herbicides will take effect and create a barrier to stop the weeds.

Every region is different from the next and depending on where you are, you might face different standards on when it’s right to lay down herbicide. Again, much of this comes down to reading the instructions on the side of the product and following them carefully. Talking to other weed control practitioners in your area and learning their procedures can’t hurt either. Herbicides can be applied by spraying with liquid, spreading with fertilizer or in granules. Then it must be watered in to create an effective weed prevention zone. Afterwards, you should be mindful not to puncture the soil, as this will create a space for weeds to grow through, thus defeating the whole reason for putting herbicide there in the first place.

Although the vast majority of chemical herbicides are perfectly safe for desirable plants and people handling the products, you must still exercise caution when using them. If the surface water runoff of the product makes its way to any nearby streams, it can contaminate the water. In general, though, chemical herbicides are safe for both the user and the environment. “Sometimes there are negative preconceptions that go with chemical herbicides,” says Sisti. “But that’s just not the case. When performed by a trained professional, they can really complement a smart ergonomic program.”

Chemicals aren’t the only way to go when using herbicides. Biological herbicides are a popular alternative, especially in eco-conscious regions such as California, Oregon and Washington, where the word ‘chemical’ tends to spark uneasiness. Not all homeowners are comfortable dappling their lawns with products that were made in a laboratory, whether that product poses any real risk or not. A biological herbicide might be just the environmentally- friendly alternative these homeowners are looking for. Likewise, public places such as schools or parks are hot spots for biological herbicides. “In terms of business, there are a certain percentage of people out there who don’t want chemicals near their house or their kids,” says Nate Elfner, owner of Elfner Landscape and Organic Lawncare, Delaware, Ohio. His company specializes in organic lawn care, using the most natural products possible. “I’m providing a viable service to those people. It’s a largely untapped market right now. I mean, these people are already buying organic food and milk and things. When they realize that they’re having their lawns chemically sprayed, they see what we have to offer is a nice alternative.” Corn gluten meal is the most widely used biological herbicide.

A byproduct of corn that’s commonly used as an animal feed, corn gluten meal is also a fast-acting pre-emergent control. As an herbicide, it releases nitrogen onto the turf, helping the grass to grow thicker and crowd out weeds. It stays effective for eight to 10 weeks. “I do one application in mid-April and then again in late August in time for autumn,” says Elfner. However, corn gluten doesn’t provide as much control as chemical herbicides. “It can be considered an herbicide, but corn gluten only has 40% control,” claims Cheryl Wilen, area IPM advisor for the University of California, San Diego, California. “It’s pretty good for crabgrass and dandelion control, but a lot of chemical companies aren’t satisfied with only 40%.”

Corn gluten meal is also considerably more expensive than chemical herbicides. Those looking for cost-friendly biological alternatives might want to consider organic mulching. Mulch is a popular weed control for areas surrounding tree trunks and flower beds. A two- to three-inch layer should be all you need to keep the weeds from sprouting. Compost can be mixed into the soil, improving the health of desirable plants and making them more competitive. This gives desirable plants more leverage to edge out weeds. In addition to pre-emergents, there are post-emergent chemical herbicides. These products are sprayed selectively onto weeds that have already germinated, killing them—but that’s another article for another time. For those in favor of biological herbicides, Sarritor, a Montreal, Canada-based pest control company, is currently developing a post-emergent product called Sclerotinia minor, a fungus that can kill broadleaf weeds. “If this product is introduced in the States, it could be the missing link for finally having a post-emergent control that’s organic,” says Elfner. One thing landscape professionals should keep in mind is that weed seeds can stay dormant inside the ground for much longer than most people imagine. “There’s been lots of studies done where they’ve excavated seeds in the soil and they can still germinate,“ says Urbanowski.

“They’ll stay underground for hundreds and hundreds of years.” Having an efficient program set in place is a great way to curtail weeds, but you can’t just apply herbicides and fertilizers once and expect the lawn to keep its pleasant appearance a year down the line. Just like your equipment, if you want to keep things in good shape, regular maintenance is in order. A good contractor should be inspecting the integrity of the lawn regularly, checking for weeds, pests, gaps in the turf, etc.

This way, whatever problems are spotted can be addressed before they become serious. Proper mowing, fertilization and aerating on an annual basis are key when it comes to maintaining healthy turf. Effective irrigation also plays an important role in weed control. Good water distribution will increase the thickness of the turf, creating a continuous sward to protect against weeds. Drainage is of particular significance. “Always watch where your system is draining,” says Wilen.

“A lot of times, areas over-saturated with water are where you’ll find weeds coming up.” What should perhaps be kept in mind more than anything else are your customers’ needs. Some customers are perfectly happy so long as they can’t see weeds sprouting from afar. Some might even enjoy the sight of a dandelion here or there. Others might be very picky. “What’s the definition of a weed?” asks Sisti. “A weed is any type of unwanted plant. But it’s all subjective in that respect. Our job is to figure out what those unwanted plants are.”

It’s up to you to determine what it is your customer expects from a lawn and to follow those expectations accordingly. From there, it’s just a matter of keeping those pesky weeds in check.